1. Field of the Invention
The present invention relates to an image reading apparatus, and particularly to an image reading apparatus in which light transmitted from a transmitting original recording medium is imaged on a solid imaging element in an imaging optical system, so as to read the information from the original.
2. Description of the Related Art
Conventionally, there are color image scanners, color photocopiers, and the like, as image reading apparatus for converting image information from original documents and the like into electric signals and importing this into a computer.
FIG. 23 is a diagram illustrating a schematic configuration of a conventional image reading apparatus. This image reading apparatus is an apparatus with a 2-to-1 scanning optical system which irradiates light onto an original document recorded on a non-transparent sheet, and processes the light reflected from the sheet, i.e., reads a reflecting original. A 2-to-1 scanning optical system means an optical system in which part of the scanning optical system operates at xc2xd the scanning speed in the sub-scanning direction, as described later.
As shown in FIG. 23, a reflecting original 103 placed on an original table glass 100 is illuminated by direct light flux from a reflecting original illuminating lamp 101 and by reflected light flux from a reflecting shade 102, and the reflected light from the reflecting original 103 is sent to a CCD 107 via a mirror 104, roof mirror 105, and imaging lens 106, where multiple unit solid imaging elements arrayed in line fashion to form the CCD 107 convert the reflected light into electrical signals, thereby forming the image in the main scanning direction.
Also, regarding image forming in the sub-scanning direction, the reflecting original illuminating lamp 101, reflecting shade 102, and mirror 104 are mechanically moved in the sub-scanning direction at a predetermined scanning speed relative to the reflecting original 103, and further the roof mirror 105 follows in the same direction at xc2xd of the predetermined scanning speed, keeping the length of the optical path from the reflecting original 103 to the CCD 107 (i.e., the conjugated relation) constant, thereby forming a two-dimensional image as a total when combined with the main scanning.
Also, particularly for color reading, the 3-line color image reading method is generally known, wherein a lamp having white spectral properties is used for the reflecting original illuminating lamp 101, and a 3-line type CCD having filters for each of the colors of RGB is used for the CCD 107, so as to simultaneously read the image information for each of the colors of RGB with a single scan on an image processing circuit, and the signals for each of the colors of RGB on the same line are overlaid to form a color image. A light source switchover color image reading method uses three lamps having the spectral distribution of each of the colors of R, G, and B, and a 1-line CCD having sensitivity over the entire white area.
It is also possible to transmit original reading system for positives, negatives, and the like, by adding a simple configuration to such image reading apparatuses.
FIG. 24 is a diagram illustrating a schematic configuration in an image reading apparatus for reading transmitting originals. This image reading apparatus also is a 2-to-1 scanning optical system. Note that the configuration of the image reading apparatus shown in FIG. 24 is the same as the configuration of the image reading apparatus shown in FIG. 23, so the same components will be denoted with the same reference numerals.
As shown in FIG. 24, the transmitting original 108 such as a positive or a negative placed on the original table glass 100 is illuminated with a transmitting original illuminating lamp 110 via a scattering plate 109 provided above, and a main scanning direction image is formed in the same manner with the transmitted light from the transmitting original 108 with the same process as that of the image recording apparatus shown in FIG. 23, i.e., by converting into electrical signals at the CCD 107 via the mirror 104, roof mirror 105, and imaging lens 106. Also regarding the image forming in the sub-scanning direction here, the transmitting original illuminating lamp 110 and mirror 104 are mechanically moved in the sub-scanning direction relative to the transmitting original 108 while maintaining the same speed and same phase, and further in the same manner as with the reflecting original, the roof mirror 105 follows in the same direction at xc2xd of the scanning speed, keeping the length of the optical path from the transmitting original 108 to the CCD 107 (i.e., the conjugated relation) at a constant, thereby forming a two-dimensional image as a total when combined with the main scanning.
Also, image reading apparatuses with integrated optical systems which is a different method from the above-described 2-to-1 scanning optical system, are also known.
FIG. 25 is a diagram illustrating the schematic configuration of a conventional integrated optical system image reading apparatus that reads reflecting originals. Note that the configuration of the image reading apparatus shown in FIG. 25 is basically the same as the configuration of the image reading apparatus shown in FIG. 23, so the same components will be denoted with the same reference numerals.
A reflecting original illuminating lamp 101, reflecting shade 102, mirrors 104a, 104b, 104c, imaging lens 106, and CCD 107 are positioned within an optical unit 111, and the optical unit 111 itself moves with respect to the reflecting original 103.
FIG. 26 is a diagram illustrating the schematic configuration of a conventional integrated optical system image reading apparatus which reads transmitting originals. Note that the configuration of the image reading apparatus shown in FIG. 26 is basically the same as the configuration of the image reading apparatus shown in FIGS. 24 and 25, so the same components will be denoted with the same reference numerals. Further, the operation of the image reading apparatus shown in FIG. 26 is the same as the operation of the image reading apparatus shown in FIG. 25, so description thereof will be omitted.
The image reading by these integrated optical system image reading apparatuses is similar to a 2-to-1 scanning optical system, but with the transmitting original reading for example, as shown in FIG. 26, the transmitting original 108 such as a positive or a negative placed on the original table glass 100 is illuminated with a transmitting original illuminating lamp 110 via a scattering plate 109 provided above, and a main scanning direction image is formed by guiding the transmitted light from the transmitting original 108 to the integrated optical system. Also with respect to the image forming in the sub-scanning direction, the transmitting original illuminating lamp 110 and optical unit 111 are mechanically moved in the sub-scanning direction relative to the transmitting original 108 while maintaining the same speed and same phase, thereby forming a two-dimensional image as a total when combined with the main scanning.
Now, with the above 2-to-1 scanning optical system and integrated optical system transmitting original image reading apparatuses, two apparatuses are known for detecting foreign matter such as dust existing on the transmitting original or damage to the film surface such as scratches (this detection hereafter will be referred to as xe2x80x9cforeign matter/scratch detectionxe2x80x9d), and removing the effects of the foreign matter and scratches by image processing from the read image. The following is a description of the foreign matter/scratch detection functions.
FIG. 27 is a diagram illustrating a first foreign matter/scratch detecting apparatus. This apparatus is particular a 2-to-1 scanning optical system, and basically has the same configuration as the image processing apparatus shown in FIG. 24. The same components will be denoted with the same reference numerals, and description thereof will be omitted.
The characteristic configuration of the first foreign matter/scratch detecting apparatus is that the transmitting original illuminating lamp 110 has a light-emitting intensity 112 in a particular infrared range other than the visible light range, as shown in FIG. 28. FIG. 28 is a diagram illustrating the spectral intensity distribution properties of the transmitting original illuminating lamp 110, with the maximum of the light-emitting intensity for the vertical axis being set at a value 1 and normalized.
Further, an infrared cutout filter 113 or a visible light cutout filter 114 is inserted in the optical path between the imaging lens 106 and the CCD 107 shown in FIG. 27. The infrared cutout filter 113 has spectral transmittance properties such as indicated by the broken line in FIG. 29, and the visible light cutout filter 114 has spectral transmittance properties such as indicated by the single-dot broken line in FIG. 29. FIG. 29 shows both the spectral transmittance of the infrared cutout filter 113 and the visible light cutout filter 114, and also illustrates the relative light emitting intensity (indicated by a solid line) of the transmitting original illuminating lamp 110.
In the reading mode for reflecting originals and transmitting originals, the infrared cutout filter 113 is inserted in the optical path so as to transmit light in the visible range, and the light-emitting intensity 112 of the transmitting original illuminating lamp 110 at a particular infrared range is cut out. Also, in the foreign matter/scratch detecting mode, the visible light cutout filter 114 is inserted in the optical path instead of the infrared cutout filter 113, the light-emitting intensity 112 is transmitted, and light in the visible range is cut out.
Next, the process for detection of foreign matter and scratches will be described.
First, in the reading mode for reflecting originals and transmitting originals, the infrared cutout filter 113 is inserted in the optical path and the original illuminating lamp 110 is turned on. At this time, the light-emitting intensity 112 of the transmitting original illuminating lamp 110 at a particular infrared range is cut out by the infrared cutout filter 113, so a suitable image without effects of infrared light can be obtained from the CCD 107.
Next, in the foreign matter/scratch detecting mode, the visible light cutout filter 114 is first inserted in the optical path and the transmitting original illuminating lamp 110 is turned on. At this time, the light in the visible range of the original illuminating lamp 110 is cut out by the visible light cutout filter 114, so only the light-emitting intensity 112 of the transmitting original illuminating lamp 110 at the particular infrared range reaches the CCD 107. Now, the transmitting original 108 such as a positive or negative film transmits infrared light regardless of the photosensitive image thereof, so only the image of objects such as foreign matter, dust, scratches, etc., which physically shield the optical path is imaged on the CCD 107 as an inverted image. This foreign matter/scratch detecting image and the image obtained by the above-described reading mode are subjected to image processing, the image of foreign matter and scratches is removed from the image obtained by the reading mode, thereby obtaining a suitable image.
FIG. 30 is a diagram illustrating a second foreign matter/scratch detecting apparatus. This apparatus is also a 2-to-1 scanning optical system, and basically has the same configuration as the image processing apparatus shown in FIG. 24. The same components will be denoted with the same reference numerals, and description thereof will be omitted.
The characteristic configuration of the second foreign matter/scratch detecting apparatus is that instead of the transmitting original illuminating lamp 110, an LED 115 which emits light of the colors R, G, and B is positioned in close proximity to a foreign matter/scratch detecting light source 117 having a light-emitting intensity in a particular infrared range other than the visible light range. The LED 115 is a light source which only emits light in the visible range, as shown in FIG. 31, and the foreign matter/scratch detecting light source 117 has light-emitting intensity in a particular infrared range 116 other than the visible light range, as shown in FIG. 31. FIG. 31 is a diagram illustrating the light-emitting intensity properties of the LED 115 and the foreign matter/scratch detecting light source 117, with the R-light-emitting properties of the LED 115 represented with a broken line, the G-light-emitting properties with a single-dot broken line, the B-light-emitting properties with a solid line, and the properties of the foreign matter/scratch detecting light source 117 with a two-dot broken line.
The process for detection of foreign matter and scratches with the second foreign matter/scratch detecting apparatus will now be described.
In the reading mode for reflecting originals and transmitting originals, the main scanning image reading is performed in the state of the R, G, and B colors of the LED 115 lit, and the foreign matter/scratch detecting light source 117 off. On the other hand, in the foreign matter/scratch detecting mode, image reading of foreign matter, dust, scratches, etc., is performed in the same manner as with the first foreign matter/scratch detecting apparatus, with the R, G, and B colors of the LED 115 off and the foreign matter/scratch detecting light source 117 lit. Both images thus obtained are subjected to image processing, to obtain a suitable image while suppressing image deterioration due to foreign matter and scratches.
However, the above two conventional apparatuses have the following problems.
With the first foreign matter/scratch detecting apparatus, the inserting/extracting mechanism for the two filters makes the foreign matter/scratch detecting apparatus complex. That is, this apparatus is advantageous in that the transmitting original illuminating lamp 110 doubles as a visible light range illumination necessary for the image reading mode and the infrared range illumination necessary in the foreign matter/scratch detecting mode, so that the configuration around the lamp is the same configuration as conventional configurations, but this arrangement requires two filters 113 and 114 with differing spectral transmittance properties, and further a configuration is necessary wherein the infrared cutout filter 113 and visible light cutout filter 114 are selectively inserted to and extracted from the optical path according to the mode, thus making the configuration of the apparatus complex.
Also, with the first foreign matter/scratch detecting apparatus, in the event that a fluorescent lamp or xenon lamp is used as the lamp having light emitting intensity in the visible light range and infrared range, the light-emitting intensity in the infrared range thereof is extremely small when compared to the light-emitting intensity thereof in the visible light range, and also fluorescent lamps and xenon lamps have instability with respect to environmental temperature changes over time. Further, in the event of using a fluorescent lamp or xenon lamp, the light-emitting intensity in the infrared range which is small is further reduced by using a filter at the time of detecting foreign matter and scratches, meaning that noise on the image when the CCD is dark is not negligible, and deterioration in the process of removing the foreign matter/scratch image is unavoidable.
With the second foreign matter/scratch detecting apparatus, the visible light amount is insufficient. This arrangement is advantageous in comparison with the first foreign matter/scratch detecting apparatus in that filters are not needed, but the amount of light from the LED with the R, G, and B colors used as the light source for emitting light only in the visible light range is drastically smaller than that of fluorescent lamps or xenon lamps, meaning that the image reading speed with reduction optical systems using projecting lenses is extremely slow, and thus impractical.
Accordingly, it is an object of the present invention to provide an image reading apparatus capable of suitably reading image information recorded on a transmitting original recording medium.
To this end, according to an embodiment of the present invention, an image reading apparatus, which images transmitted light from a transmitting original recording medium on a solid imaging element in an imaging optical system so as to read information from the original includes:
a first light source that emits light primarily in the visible light range and in a first infrared range.
A second light source emits light primarily in a second infrared range that does not include the first infrared range.
An infrared cutout unit disposed within the optical path, which does not transmit the light in the first infrared range but does transmit light in the second infrared range.
An image information reading unit guides transmitted light from the transmitting original recording medium based on light from the first light source to the solid imaging element via the infrared cutout unit. The image information reading unit reads image information recorded on the transmitting original recording medium based on signals obtained from the solid imaging element.
A defect information reading unit guides transmitted light from the transmitting original recording medium based on light from the second light source to the solid imaging element via the infrared cutout unit. The defect information reading unit reads defect information other than recorded image information existing on the transmitting original recording medium based on signals obtained from the solid imaging element.
A correcting unit is adapted to remove the defect information read by the defect information reading unit, from the image information read by the image information reading unit.
Also, according to another embodiment of the present invention, an image reading apparatus, which images transmitted light from a transmitting original recording medium on a solid imaging element in an imaging optical system so as to read information from the original includes:
a first light source which emits light at least in the visible light range and a second light source which emits light only in the infrared range.
An infrared cutout filter that does not transmit light in the infrared range and an image information reading unit that guides transmitted light from the transmitting original recording medium based on light from the first light source to the solid imaging element via the infrared cutout filter. The image reading unit reads image information recorded on the transmitting original recording medium based on signals obtained from the solid imaging element.
A defect information reading unit guides transmitted light from the transmitting original recording medium based on light from the second light source to the solid imaging element without using the infrared cutout filter, and reading defect information other than recorded image information existing on the transmitting original recording medium based on signals obtained from the solid imaging element.
A correcting unit removes the defect information read by the defect information reading unit, from the image information read by the image information reading unit.
According to such a configuration, image information on a transmitting original recording medium can be read suitably.
Further objects, features, and advantages of the present embodiment will become apparent from the following description of the preferred embodiments with reference to the attached drawings.